Since the identification of tissue transglutaminase (tTG) as an antigen to endomysial antibodies (EMA), several antigen-specific immunoassays have been reported for screening for celiac disease (CD). The first objective was to evaluate the suitability for CD screening of three different IgA tTG ELISAs, two of them based on guinea pig liver tTG (GP-tTG) (an internal ELISA with a partially purified extract and a commercial ELISA with purified GP). -tTG) and a third recombinant human tTG ELISA (RH-tTG). The results are compared with EMA and with the final clinical diagnosis. A second objective was to analyze antibody reactivities in those patients with anti-tTG and EMA discrepancies.
ELISA and EMA tests were used to measure anti-tTG IgA levels in sera from 259 patients (107 had CD and 72 had type I diabetes mellitus).
The purified GP-tTG ELISA was highly sensitive (97.7%) and specific (98.8%) in detecting CD, almost matching EMA. The Rh-tTG ELISA did not improve the sensitivity of EMA, but its specificity was slightly higher. Immunoblot analysis with partially purified GP-tTG extract, the most commonly used antigen for the detection of anti-tTG, showed that most of the false positives were due to IgA reactivities to contaminating proteins present in the liver antigen extract. This low specificity was particularly problematic in diabetics.
Purified tTG ELISAs, either with purified guinea pig liver or with recombinant human antigens, can be used as quantitative and observer-independent alternatives to traditional and time-consuming EMA in CD screening.
What is a blood test?
By taking and testing a small sample of a person’s blood, doctors can detect many types of diseases and conditions. Blood tests help doctors check how the body’s organs are working and see if medical treatments are helpful. To help your child prepare for a blood test, find out if she needs to fast (not eat or drink) or stop taking medicine before the test. Explain what to expect during the test. If your child is anxious about it, work together on ways to stay calm.
What is a tissue transglutaminase IgA (tTG-IgA) test?
A tissue transglutaminase IgA (TTG-IgA) test is used to help doctors diagnose celiac disease. In this autoimmune disorder, the immune system mistakenly thinks that gluten, a protein in wheat, barley, rye, and oats, is a foreign invader. It makes antibodies that attack an enzyme in the intestines called tissue transglutaminase (tTG). Antibodies (also called immunoglobulins) are proteins that recognize and kill germs.
Why are tTG-IgA tests done?
Doctors may order a tTG-IgA test if a child has symptoms of celiac disease, such as poor growth, abdominal pain, constipation, vomiting, diarrhoea, or skin rashes. The test may also be done if a child has a condition that makes the celiac disease more likely (such as type 1 diabetes), thyroid disease, or a family member with celiac disease.
How do we prepare for a tTG-IgA test?
For the test to be accurate, your child must be on a gluten-containing diet until the test is complete.